We have successfully developed a membrane reactor for decomposing hydrogen sulfide into hydrogen using an amorphous silica membrane for the first time. The membrane was prepared by the CVD method with tetramethoxysilane and oxygen, and showed excellent hydrogen permeance at 873 K of the order of 10(-7) mol m(-2) s(-1) Pa-1 and high hydrogen/nitrogen permselectivity of 10(4). The membrane reactor constructed with our membrane and a commercially available catalyst decomposed hydrogen sulfide into hydrogen with higher conversion than the equilibrium conversion. This conversion enhancement was because of the selective extraction of hydrogen from the reaction side to the permeate side by the silica membrane. (c) 2008 Elsevier B.V. All rights reserved.